commensal

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

adj. Of, relating to, or characterized by a symbiotic relationship in which one species is benefited while the other is unaffected.

n. An organism participating in a symbiotic relationship in which one species derives some benefit while the other is unaffected.

from Wiktionary, Creative Commons Attribution/Share-Alike License

adj. of a form of symbiosis in which one organism derives a benefit while the other is unaffected

n. An organism partaking in a commensal relationship.

from the GNU version of the Collaborative International Dictionary of English

adj. Having the character of a commensal.

n. One who eats at the same table.

n. An animal, not truly parasitic, which lives in, with, or on, another, partaking usually of the same food. Both species may be benefited by the association.

from The Century Dictionary and Cyclopedia

Eating together at the same table.

In zoology and botany, living with as a tenant or coinhabitant, but not as a parasite; inquiline. See II., 2.

n. One who eats at the same table with another or others.

n. In zoology and botany, one of two animals or plants which live together, but neither at the expense of the other; an animal or a plant as a tenant, but not a true parasite, of another; an inquiline.

Over millions of years, it has learned to live benignly on human skin and in human nostrils, in a microscopic intimacy that biologists call “commensal,” from the Latin words for “being at table together.”

Furthermore, human commensal species, such as great-tailed grackle Quiscalus mexiccanus and bronzed cowbird Molothrus aeneus, normally increase in number around human settlements and result in the loss of nesting success in other birds.

When I took a human-animal interaction class in college, we were taught that cats are not properly considered domesticated but commensal, like a remora or a cowbird but with much more sophisticated social engineering!